Transflective LCD

ABSTRACT

A transflective LCD. The transflective LCD includes multiple pixels. Each pixel includes a reflective cell and a transmission cell. The reflective cell has a first storage capacitor and a first active device, receiving a first driving voltage and coupling to the first capacitor. The transmission cell has a second storage capacitor and a second active device, receiving a second driving voltage and coupling to the second capacitor. The first driving voltage and the second voltage are generated according to a reflective gamma curve and a trans gamma curve respectively.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a transflective LCD, andparticularly to a transflective LCD driven by bi-gamma curve.

[0003] 2. Description of the Related Art

[0004] A pixel of the conventional transflective VCD has a transmissioncell and a reflective cell. Unavoidably, the reflective cell has anearly double phase difference nearly double that of the transmissioncell. Reduction of cell gap of the reflective cell to approach that ofthe transmission cell has been adopted in the past to address thisissue. FIG. 7A shows a perspective diagram of a pixel of a conventionaltransflective LCD. The pixel includes a reflective cell 10 and atransmission cell 20. The reflective cell 20 has a reflective film 12and a cell gap d1. The transmission cell 20 has a cell gap d2. Anequivalent circuit is shown in FIG. 7B. The reflective cell 10 and thetransmission cell 20 are both coupled to a storage capacitor Cs and aTFT (thin-film-transistor) transistor T1. Thus, only driving voltage isafford to supply. The anti-inversion approach adjusts the cell gap d1and the cell gap d2 to the same phase difference. The cell gap d1 and d2must be optimized to fit the LCD's operation mode, an approach that isdifficult to adjust.

SUMMARY OF THE INVENTION

[0005] It is therefore an object of the present invention to provide atransflective LCD that achieves optimal reflectivity and transmittance.

[0006] To achieve the above objects, the present invention provides apixel with reflective cell and transmission cells. The reflective celland the transmission cell both have a storage capacitor and a TFTtransistor for different driving voltages. The driving voltage for thereflective cell can have any phase difference in cell gap such as halfwave or quarter wave. The driving voltage for the transmission cell canhave any phase difference in cell gap such as half wave or quarter wave.

[0007] A driving method for the transflective LCD scans all reflectivecells first in a frame period, with all transmission cells are scannedlater.

[0008] Another driving method for the transflective LCD scans allreflective cells of one row first in the row's active period, and alltransmission cells of one row thereof latter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The aforementioned objects, features and advantages of thisinvention will become apparent by referring to the following detaileddescription of the preferred embodiments with reference to theaccompanying drawings, wherein:

[0010]FIG. 1A shows a perspective diagram in a pixel's structure of atransflective LCD of the present invention.

[0011]FIG. 1B shows an equivalent circuit of the pixel in FIG. 1A.

[0012]FIG. 2A shows a reflectivity gamma curve RV1 for quarter wavephase difference in the transmission cell.

[0013]FIG. 2B shows a transmittance gamma curve TV1 for quarter wavephase difference in the transmission cell.

[0014]FIG. 2C shows a reflectivity gamma curve RV1 for half wave phasedifference in the transmission cell.

[0015]FIG. 2D shows a transmittance gamma curve TV1 for half wave phasedifference in the transmission cell.

[0016]FIG. 3A shows a schematic diagram of a pixel P22 in FIG. 3B.

[0017]FIG. 3B shows a block diagram of a LCD in the first embodiment.

[0018]FIG. 3C shows a diagram of all waveforms in FIG. 3B.

[0019]FIG. 3D shows a diagram of all waveforms in FIG. 3B.

[0020]FIG. 3E shows another block diagram of a LCD in the firstembodiment.

[0021]FIG. 4A shows a schematic diagram of a pixel P22 in FIG. 4B.

[0022]FIG. 4B shows a block diagram of a LCD in the second embodiment.

[0023]FIG. 4C shows a diagram of all waveforms in FIG. 4B.

[0024]FIG. 4D shows a diagram of all waveforms in FIG. 4B.

[0025]FIG. 4E shows another block diagram of a LCD in the secondembodiment.

[0026]FIG. 5A shows a schematic diagram of a pixel P22 in FIG. 5B.

[0027]FIG. 5B shows a block diagram of a LCD in the third embodiment.

[0028]FIG. 6 shows a block diagram of a LCD in the fourth embodiment.

[0029]FIG. 7A shows a prospective diagram of a pixel of a conventionaltransflective LCD.

[0030]FIG. 7B shows an equivalent circuit of the pixel in FIG. 7A.

DETAILED DESCRIPTION OF THE INVENTION

[0031]FIG. 1A shows a perspective diagram in a pixel's structure of atransflective LCD of the present invention. The pixel includes areflective cell 10 and a transmission cell. The reflective cell 10 has areflective film 12 and a cell gap d1. The transmission cell 20 has acell gap d2. FIG. 1B shows an equivalent circuit of the pixel. In thereflective cell 10, an equivalent capacitor of the reflective cell 10 isrepresented by Clc1, a storage capacitor is Cs1, and a TFT transistor isT1. In the transmission cell 20, an equivalent capacitor of thetransmission cell 10 is represented by Clc2, a storage capacitor is Cs2,and a TFT transistor is T2. The TFT transistor T2 and T1 can be disposedunder the reflective film 12.

[0032] Operating in quarter wave phase difference of the transmissioncell 20, a reflectivity gamma curve RV1 showing reflectivity versusdriving voltage VR of the reflective cell 10 is shown in FIG. 2A.Because the phase difference through the reflective cell 10 is twicethat of the transmission cell 20, the maximum reflectivity occurs inhalf wave. A transmittance gamma curve TV1 showing transmittance versusdriving voltage VT of the transmission cell 10 is shown in FIG. 2B, andthe maximum transmittance occurs in quarter wave.

[0033] Operating in half wave phase difference of the transmission cell20, a reflectivity gamma curve RV2 showing reflectivity versus drivingvoltage VR of the reflective cell 10 is shown in FIG. 2C. Because thephase difference through the reflective cell 10 is twice that of thetransmission cell 20, the maximum reflectivity occurs in half wave. Whenthe phase difference exceeds half wave, the reflectivity decrease withdriving voltage VR. A transmittance gamma curve TV2 showingtransmittance versus driving VT of the transmission cell 10 is shown inFIG. 2D, and the maximum transmittance occurs in half wave.

[0034] Because the pixel in the present invention has two TFTtransistors T1 and T2, and two storage capacitors Cs1 and Cs2, tocontrol driving voltage VR and VT respectively, the reflective cell 10and transmission cell 20 achieve the same phase difference withoutadjusting the cell gap d1 and d2. The driving voltage VR for thereflective cell 10 can be driven by the quarter wave gamma curve RV1 orby half wave gamma curve RV2. The driving voltage VT for thetransmission cell 20 can be driven by the quarter wave gamma curve TV1or by half wave gamma curve TV2. The reflective cell 10 and thetransmission cell 20 are corrected by reflectivity and transmittancegamma curve respectively to meet requirements.

[0035] In power down mode, only the reflective cells 10 are or thetransmission cells 20 are powered. As well as turning off back lamps,driving circuits for transmission cells 20 can be turned off for morepower saving.

[0036] The First Embodiment

[0037]FIG. 3B shows a block diagram of a LCD in the first embodiment.The LCD includes a TFT transistor array 300, an image-signal drivingcircuit 100, a scan-signal driving circuit 200, and a scan-signaldriving circuit 220. FIG. 3A shows a schematic diagram of a pixel P22 inFIG. 3B. Other pixels in FIG. 3B have the same schematic as shown inFIG. 3A. The pixel P22 has a reflective cell 10 and a transmission cell20, and thus requires two sets of TFT transistors and storagecapacitors.

[0038] The TFT transistor T1 is disposed at the intersection of row G2Aand column D2A. A gate of the TFT transistor T1 is coupled to row G2A, adrain of the TFT transistor T1 is coupled to column D2A, and a source ofthe TFT transistor T1 is coupled to Clc1 and storage capacitor Cs1. TheTFT transistor T2 is disposed at the intersection of row G2B and columnD2A. A gate of the TFT transistor T1 is coupled to row G2B, a drain ofthe TFT transistor T1 is coupled to column D2A, and a source of the TFTtransistor T2 is coupled to Clc2 and storage capacitor Cs2. All Pixelsin the TFT transistor array 300 have the same wiring structure.

[0039] The scan-signal driving circuit 200 generates scan signals fed togates of TFT transistors T1 via rows G1A-G4A. The scan-signal drivingcircuit 220 generates scan signals fed to gates of TFT transistors T2via rows G1B-G4B. The image-signal driving circuit 100 generates imagesignals corresponding to scan signals fed to reflective cell Clc1 ortransmission cell Clc2 via columns D1A-D4A and TFT transistor array 300.

[0040] A driving method in the first embodiment scans all reflectivecells first, and all transmission cells later. FIG. 3C shows a diagramof all waveforms in FIG. 3B. The GAMMA1 can select the reflectivitygamma curve RV1 or RV2, thereby transferring the image signals. TheGAMMA2 can select the transmittance gamma curve TV1 or TV2, therebytransferring the image signals. As shown in FIG. 3C, a frame period fd1is divided into a GAMMA1 period TG1 and a GAMMA2 period TG2. In GAMMA1period TG1, the image-signal driving circuit 100 feeds image signals toreflective cells Clc1 and storage capacitors Cs1 via columns D1A-D4A inperiods TA1, TA2, TA3, and TA4, rows G1A-G4A respectively. In GAMMA2period TG2, the image-signal driving circuit 100 feeds image signals totransmission cells Clc2 and storage capacitors Cs2 via columns D1A-D4Ain periods TB1, TB2, TB3, and TB4, activating rows G1B-G4B respectively.

[0041] Another driving method in the first embodiment scans allreflective cells of one row first in one row's active period, and alltransmission cells of one row later in one row's active period. FIG. 3Dshows a diagram of all waveforms in FIG. 3B. As shown in FIG. 3D, in aframe fd1, GAMMA1 is active in periods TGA1, TGA2, TGA3, TGA4, andGAMMA2 is active in periods TGB1, TGB2, TGB3, and TGB4. Rows active insequence periods G1A-G1B-G2A-G2B-G3A-G3B-G4A-G4B corresponding to thesequence periods TGA1-TGB1-TGA2-TGB2-TGA3-TGB3-TGA4-TGB4 that GAMMA1 andGAMMA2 are active alternatively. In periods TGA1, TGA2, TGA3, and TGA4,the image-signal driving circuit 100 feeds image signals to reflectivecell Clc1 and storage capacitor Cs1 via columns D1A-D4A in periods thatrows G1A-G4A are active respectively. In periods TGB1, TGB2, TGB3, andTGB4, the image-signal driving circuit 100 feeds image signals toreflective cell Clc2 and storage capacitor Cs2 via columns D1A-D4A inperiods when rows G1B-G4B are active respectively. The driving method inFIG. 3E is the same as that in 3B. The scan-signal driving circuit 200and 220 are replaced by the scan-signal driving circuit 200 and amultiplex 250. The multiplex 250 switches between rows G1A-G4A and rowsG1B-G4B.

[0042] The Second Embodiment

[0043]FIG. 4B shows a block diagram of a LCD in the second embodiment.The LCD includes a TFT transistor array 300, an image-signal drivingcircuit 100 and 120, and a scan-signal driving circuit 200. FIG. 4Ashows a schematic diagram of a pixel P22 in FIG. 4B. Other pixels inFIG. 4B have the same schematic as shown in FIG. 4A. The pixel P22 has areflective cell 10 and a transmission cell 20, and thus requires twosets of TFT transistors and storage capacitors.

[0044] The TFT transistor T1 is disposed at the intersection of row G2Aand column D2A. A gate of the TFT transistor T1 is coupled to row G2A, adrain of the TFT transistor T1 is coupled to column D2A, and a source ofthe TFT transistor T1 is coupled to Clc1 and storage capacitor Cs1. TheTFT transistor T2 is disposed at the intersection of row G2A and columnD2B. A gate of the TFT transistor T1 is coupled to row G2A, a drain ofthe TFT transistor T2 is coupled to column D2B, and a source of the TFTtransistor T2 is coupled to Clc2 and storage capacitor Cs2. All Pixelsin the TFT transistor array 300 have the same wiring structure. Thescan-signal driving circuit 200 generates scan signals fed to gates ofTFT transistors T1 or T2 via rows G1A-G4A. The image-signal drivingcircuit 100 generates image signals corresponding to scan signals fed toreflective cell Clc1 via columns D1A-D4A and TFT transistor array 300.The image-signal driving circuit 120 generates image signalscorresponding to scan signals fed to transmission cell Clc2 via columnsD1B-D4B and TFT transistor array 300.

[0045] A driving method in the second embodiment scans all reflectivecells first, and all transmission cells later in a frame periods fd1.FIG. 4C shows a diagram of all waveforms in FIG. 4B. The GAMMA1 canselect the reflectivity gamma curve RV1 or RV2, thereby transferring theimage signals. The GAMMA2 can select the transmittance gamma curve TV1or TV2, thereby transferring the image signals. As shown in FIG. 4C, aframe period fd1 is divided into a GAMMA1 period TG1 and a GAMMA2 periodTG2. In GAMMA1 period TG1, the image-signal driving circuit 100 feedsimage signals to reflective cell Clc1 and storage capacitor Cs1 viacolumns D1A-D4A in periods TA1, TA2, TA3, and TA4, when rows G1A-G4A areactive respectively. In GAMMA2 period TG2, the image-signal drivingcircuit 120 feeds image signals to transmission cells Clc2 and storagecapacitors Cs2 via columns D1B-D4B in periods TB1, TB2, TB3, and TB4,when rows G1A-G4A are active respectively.

[0046] Another driving method in the second embodiment scans allreflective cells of one row first in the row's active period, and alltransmission cells of the row later in the row's active period. FIG. 4Dshows a diagram of all waveforms in FIG. 4B. As shown in FIG. 4D, in aframe fd1, GAMMA1 is active in periods TGA1, TGA2, TGA3, TGA4, andGAMMA2 is active in periods TGB1, TGB2, TGB3, and TGB4. Rows are activein sequence periods G1A-G2A-G3A-G4A. Row G1A is active in periods TGA1,TGB1 corresponding to GAMMA1 and GAMMA2 becoming active alternatively.Row G2A is active in periods TGA2, TGB2 corresponding to GAMMA1 andGAMMA2 becoming active alternatively. Row G3A is active in periods TGA3,TGB3 corresponding to GAMMA1 and GAMMA2 becoming active alternatively.Row G4A is active in periods TGA4, TGB4 corresponding to GAMMA1 andGAMMA2 becoming active alternatively. In periods TGA1, TGA2, TGA3, andTGA4, the image-signal driving circuit 100 feeds image signals toreflective cell Clc1 and storage capacitor Cs1 via columns D1A-D4A inperiods that rows G1A-G4A are active respectively. In periods TGB1,TGB2, TGB3, and TGB4, the image-signal driving circuit 120 feeds imagesignals to reflective cell Clc2 and storage capacitor Cs2 via columnsD1B-D4B in periods when rows G1A-G4A are active respectively.

[0047] The driving method in FIG. 4E is the same as that in 4B. Theimage-signal driving circuit 100 and 120 are replaced by theimage-signal driving circuit 100 and a multiplex 150. The multiplex 150switches between columns D1A-D4A and columns D1B-D4B.

[0048] The Third Embodiment

[0049]FIG. 5B shows a block diagram of a LCD in the first embodiment.The LCD includes a TFT transistor array 300, an image-signal drivingcircuit 100,120, and a scan-signal driving circuit 200,220. FIG. 5Ashows a schematic diagram of a pixel P22 in FIG. 5B. Other pixels inFIG. 5B have the same schematic as shown in FIG. 5A. The pixel P22 has areflective cell 10 and a transmission cell 20, and thus requires twosets of TFT transistors and storage capacitors.

[0050] The TFT transistor T1 is disposed at the intersection of row G2Aand column D2A. A gate of the TFT transistor T1 is coupled to row G2A, adrain of the TFT transistor T1 is coupled to column D2A, and a source ofthe TFT transistor T1 is coupled to Clc1 and storage capacitor Cs1. TheTFT transistor T2 is disposed at the intersection of row G2B and columnD2B. A gate of the TFT transistor T1 is coupled to row G2B, a drain ofthe TFT transistor T1 is coupled to column D2B, and a source of the TFTtransistor T2 is coupled to Clc2 and storage capacitor Cs2. All Pixelsin the TFT transistor array 300 have the same wiring structure.

[0051] The scan-signal driving circuit 200 generates scan signals fed togates of TFT transistors T1 via rows G1A-G4A. The scan-signal drivingcircuit 220 generates scan signals fed to gates of TFT transistors T2via rows G1B-G4B. The image-signal driving circuit 100 generates imagesignals corresponding to scan signals fed to reflective cell Clc1 viacolumns D1A-D4A and TFT transistor array 300. The image-signal drivingcircuit 120 generates image signals corresponding to scan signals fed totransmission cell Clc2 via columns D1B-D4B and TFT transistor array 300.

[0052] A driving method in the third embodiment scans all reflectivecells first in a frame period fd1, and all transmission cells later.FIG. 3C shows a diagram of all waveforms in FIG. 5B. The GAMMA1 canselect the reflectivity gamma curve RV1 or RV2, thereby transferring theimage signals. The GAMMA2 can select the transmittance gamma curve TV1or TV2, thereby transferring the image signals. As shown in FIG. 3C, aframe period fd1 is divided into a GAMMA1 period TG1 and a GAMMA2 periodTG2. In GAMMA1 period TG1, the image-signal driving circuit 100 feedsimage signals to reflective cells Clc1 and storage capacitors Cs1 viacolumns D1A-D4A in periods TA1, TA2, TA3, and TA4, when rows G1A-G4A areactive respectively. In GAMMA2 period TG2, the image-signal drivingcircuit 100 feeds image signals to transmission cells Clc2 and storagecapacitors Cs2 via columns D1A-D4A in periods TB1, TB2, TB3, and TB4,when rows G1B-G4B are active respectively.

[0053] Another driving method in the third embodiment scans allreflective cells of one row first in the row's active period, and alltransmission cells of one row scanned later in the row's active period.FIG. 3D shows a diagram of all waveforms in FIG. 5B. As shown in FIG.3D, in a frame fd1, GAMMA1 is active in periods TGA1, TGA2, TGA3, TGA4,and GAMMA2 is active in periods TGB1, TGB2, TGB3, and TGB4. Rows areactive in sequence in periods G1A-G1B-G2A-G2B-G3A-G3B-G4A-G4Bcorresponding to the sequence periodsTGA1-TGB1-TGA2-TGB2-TGA3-TGB3-TGA4-TGB4 GAMMA1 and GAMMA2 becomingactive alternatively. In periods TGA1, TGA2, TGA3, and TGA4, theimage-signal driving circuit 100 feeds image signals to reflective cellClc1 and storage capacitor Cs1 via columns D1A-D4A in periods when rowsG1A-G4A are active respectively. In periods TGB1, TGB2, TGB3, and TGB4,the image-signal driving circuit 120 feeds image signals to reflectivecell Clc2 and storage capacitor Cs2 via columns D1B-D4B when rowsG1B-G4B are active respectively.

[0054] The Fourth Embodiment

[0055]FIG. 6B shows a block diagram of a LCD in the first embodiment.The LCD includes a TFT transistor array 300, an image-signal drivingcircuit 100, a scan-signal driving circuit 200, and multiplex 150, 250.FIG. 5A shows a schematic diagram of a pixel P22 in FIG. 6B. Otherpixels in FIG. 6B have the same schematic as shown in FIG. 5A.

[0056] The scan-signal driving circuit 200 generates scan signals fed togates of TFT transistors T1 via rows G1A-G4A selected by the multiplex250 or to gates of TFT transistors T2 via rows G1B-G4B selected by themultiplex 250. The image-signal driving circuit 100 generates imagesignals corresponding to scan signals fed to reflective cell Clc1 viacolumns D1A-D4A selected by the multiplex 150 and TFT transistor array300 or to transmission cell Clc2 via columns D1B-D4B selected by themultiplex 150 and TFT transistor array 300.

[0057] A driving method in the fourth embodiment scans all reflectivecells first in a frame period fd1, and all transmission cells later.FIG. 3C shows a diagram of all waveforms in FIG. 6B. The GAMMA1 canselect the reflectivity gamma curve RV1 or RV2, thereby transferring theimage signals. The GAMMA2 can select the transmittance gamma curve TV1or TV2, thereby transferring the image signals. As shown in FIG. 3C, aframe period fd1 is divided into a GAMMA1 period TG1 and a GAMMA2 periodTG2. In GAMMA1 period TG1, switches S2 of the multiplex 250 are atposition 3, switches S1 of the multiplex 150 are at position 1, and theimage-signal driving circuit 100 feeds image signals to reflective cellClc1 and storage capacitor Cs1 via columns D1A-D4A in periods TA1, TA2,TA3, and TA4 that rows G1A-G4A are active respectively. In GAMMA2 periodTG2, switches S2 of the multiplex 250 are at position 4, switches S1 ofthe multiplex 150 are at position 2, and the image-signal drivingcircuit 100 feeds image signals to transmission cell Clc2 and storagecapacitor Cs2 via columns D1B-D4B in periods TB1, TB2, TB3, and TB4 whenrows G1B-G4B are active respectively.

[0058] Another driving method in the fourth embodiment scans allreflective cells of one row first in the row's active period, and alltransmission cells later in the row's active period. FIG. 3D shows adiagram of all waveforms in FIG. 6B. As shown in FIG. 3D, in a framefd1, GAMMA1 is active in periods TGA1, TGA2, TGA3, TGA4, switches S1 ofthe multiplex 150 are at position 1, and switches S2 of the multiplex250 are at position 3. In a frame fd1, GAMMA2 is active in periods TGB1,TGB2, TGB3, and TGB4, switches S1 of the multiplex 150 are at position2, and switches S2 of the multiplex 250 are at position 4. Rows areactive in sequence periods G1A-G1B-G2A-G2B-G3A-G3B-G4A-G4B correspondingto the sequence periods TGA1-TGB1-TGA2-TGB2-TGA3-TGB3 -TGA4-TGB4 whenGAMMA1 and GAMMA2 are active alternatively. In period TGA1, TGA2, TGA3,and TGA4, the image-signal driving circuit 100 feeds image signals toreflective cell Clc1 and storage capacitor Cs1 via columns D1A-D4A inperiods when rows G1A-G4A are active respectively. In period TGB1, TGB2,TGB3, and TGB4, the image-signal driving circuit 100 feeds image signalsto reflective cell Clc2 and storage capacitor Cs2 via columns D1B-D4B inperiods that rows G1B-G4B are active respectively.

[0059] Although the present invention has been described in itspreferred embodiments, it is not intended to limit the invention to theprecise embodiments disclosed herein. Those who are skilled in thistechnology can still make various alterations and modifications withoutdeparting from the scope and spirit of this invention. Therefore, thescope of the present invention shall be defined and protected by thefollowing claims and their equivalents.

What is claimed is:
 1. A transflective LCD comprising: plural pixelswherein each pixel comprises a reflective cell and a transmission cell,wherein the reflective cell has a first storage capacitor and a firstactive device, receiving a first driving voltage and coupling to thefirst capacitor, and the transmission cell has a second storagecapacitor and a second active device, receiving a second driving voltageand coupling to the second capacitor.
 2. The transflective LCD asclaimed in claim 1 wherein: the reflective cell has a firstliquid-crystal layer with a first cell gap; and the transmission cellhas a second liquid-crystal layer with a second cell gap.
 3. Thetransflective LCD as claimed in claim 1 wherein: the first drivingvoltage is generated according to a reflective gamma curve; and thesecond driving voltage is generated according to a transmission gammacurve.
 4. The transflective LCD as claimed in claim 3 wherein: thereflective gamma curve is used for quarter wave mode; and thetransmission gamma curve is used for quarter wave mode.
 5. Thetransflective LCD as claimed in claim 3 wherein: the reflective gammacurve is used for half wave mode; and the transmission gamma curve isused for half wave mode.
 6. The transflective LCD as claimed in claim 3wherein: the reflective gamma curve is used for half wave mode; and thetransmission gamma curve is used for quarter wave mode.
 7. Thetransflective LCD as claimed in claim 3 wherein: the reflective gammacurve is used for quarter wave mode; and the transmission gamma curve isused for half wave mode.
 8. The transflective LCD as claimed in claim 3wherein: the reflective cell has a first liquid-crystal layer with afirst cell gap; the transmission cell has a second liquid-crystal layerwith a second cell gap; the reflective gamma curve is according thephase difference through the first cell gap; and the trans gamma curveis according the phase difference through the second cell.
 9. Thetransflective LCD as claimed in claim 1 wherein: the first active devicehas a first control end coupled to a first scan line; the second activedevice has a second control end coupled to a second scan line; and thefirst driving voltage and the second driving voltage are provided by afirst driving line at different times.
 10. The transflective LCD asclaimed in claim 9 further comprising: a first scan-signal drivingcircuit coupled to the first scan line; a second scan-signal drivingcircuit coupled to the second scan line; and a first image-signaldriving circuit coupled to the first driving line.
 11. The transflectiveLCD as claimed in claim 9 further comprising: a multiplex coupled o thefirst scan line and the second scan line; a first scan-signal drivingcircuit coupled to the multiplex; and a first image-signal drivingcircuit coupled to the first driving line.
 12. The transflective LCD asclaimed in claim 1 wherein: the first active device has a first controlend; the second active device has a second control end; wherein thefirst control end and the second control end are enabled by a first scanline at different times; the first driving voltage is provided by afirst driving line; and the second driving voltage is provided by asecond driving line.
 13. The transflective LCD as claimed in claim 12further comprising a first image-signal driving circuit coupled to thefirst driving line; a second image-signal driving circuit coupled to thesecond driving line; and a first scan-signal driving circuit coupled tothe first scan line.
 14. The transflective LCD as claimed in claim 12wherein: a multiplex coupled o the first driving line and the seconddriving line; a first image-signal driving circuit coupled to themultiplex; and a first scan-signal driving circuit coupled to the firstscan line.
 15. The transflective LCD as claimed in claim 1 wherein: thefirst active device has a first control end coupled to the first scanline; the second active device has a second control end coupled to thesecond scan line; the first driving voltage is provided by a firstdriving line; and the second driving voltage is provided by a seconddriving line.
 16. The transflective LCD as claimed in claim 15 furthercomprising a first image-signal driving circuit coupled to the firstdriving line; a second image-signal driving circuit coupled to thesecond driving line; a first scan-signal driving circuit coupled to thefirst scan line; and a second scan-signal driving circuit coupled to thesecond scan line.
 17. The transflective LCD as claimed in claim 15wherein: a first multiplex coupled to the first driving line and thesecond driving line; a first image-signal driving circuit coupled to thefirst multiplex; and a second multiplex coupled to the first scan lineand the second scan line; a first scan-signal driving circuit coupled tothe second multiplex.